Motor fuel



Patented Nov. 18, 1941 iTED STATES PATENT OFFIE MOTOR FUEL ration ofDelaware No Drawing. Application August 24, 1939, Serial No. 291,684

2 Claims.

The present invention relates to improved motor fuels and method ofpreparing same and it relates more particularly to the preparation ofmotor fuels having high anti-detonation properties.

It has been known for some time that the class of chemical compoundsknown as diolefines have high anti-knock value when blended in gasolinefor use as motor fuel. However, especially when present along with otherhighly unsaturated compounds formed during the vapor phase cracking ofheavy hydrocarbons to make gasoline, they have the serious disadvantageof tending to induce the formation of large amounts of gum owing to thepeculiar susceptibility of the chemical structure of the various highlyunsaturated hydrocarbons to oxidation and polymerization or condensationand/or other chemical reactions involved in the formation of gum. Theexact mechanism of these reactions has been the subject of many theoriesand yet even today is not known with certainty, although it is believedto be a combination of oxidation and polymerization. Consequently owingto the development of serious engine troubles when motor fuels are usedwhich contain or develop very large amounts of gum, for example due tosticking of rings, valves, and other moving parts of the engine and dueto clogging up of the intake manifold, etc., motor fuels containingdiolefines have not been used with any success.

It has now been found, however, and is the primary object of the presentinvention, that the advantages of the high anti-detonation blendingproperties of the diolefines can be used Without having thedisadvantages of the tendency to form gum. This is accomplished by theuse of diolefines in purified form along with materials known as guminhibitors. Such materials have been used heretofore but not in a fuelto which purified diolefines have been added. Such gum inhibitors havebeen used to stabilize cracked gasoline against gum formation, and inspite of the fact that it is known that cracked gasoline may containsome diolefines (although the majority of these diolefines and any othereven more reactive compounds, if any are present, are generally removedby a suitable treating step such as acid treating, clay treating, etc.),yet it has never been suspected that substantial amounts of purifieddiolefines themselves could be actually added to a motor fuel, whetherderived from a virgin stock, or a cracked stock from which undesirablehighly unsaturated compounds have 50 was added for each 100 cc. of fuel.

5 analyzed and found to contain only 1.1% and 0.6% diolefines by weightrespectively, thus showing that even if large amounts of diolefines hadbeen produced by the cracking operation, they had been substantially allremoved before marketing.

In carrying out the present invention, various types of diolefines maybe used, for example, butadiene, isoprene, allene, pentadiene,cyclopentadiene, hexadiene, and other conjugated and unconjugated cyclicand straight chain diolefines and they may be added in amounts ranging,for example, from about 3 to or preferably between the limits of about 5and 10% by volume.

Various types of gum inhibitors including vari- 20 ous hydroxy and/oramino derivatives of monoor poly-nuclear aromatic hydrocarbons oralkylated derivatives thereof may be used, for example,monobenzyl-p-amino phenol, tricresol, amylp-amino phenol,alpha-naphthol, alpha-naphthylamine, etc., and they may be used invarious amounts between the approximate limits of 1 and 20 mg. perhundred cos. of fuel, depending upon the nature and quantity of thediolefines added, as well as the type of gasoline base stock used inpreparing the blend, although ordinarily the amount to be used will bebetween the approximate limits of 5 and 15 mg. per hundred cos. of fuel.

As illustrative of the invention, the following 0 examples are given:

Example 1 Butadiene was added to 65 octane number motor fuel in quantitysuflicient to make a 5% blend; 10 mg. of monobenzylp-amino phenol wasadded for each one hundred cc. of fuel. The resulting blend had anoctane number of 72.3, a breakdown time of 16 hours (2# drop at 100 C.)and a copper dish gum of 3.1 mg./100 cc.

Example 2 Isoprene was added to a 73.9 octane number motor fuel inquantity suflicient to make a 5% blend; 10 mg. of monobenzyl-p-aminophenol The resulting blend had an octane number of 76.8, a breakdowntime of 16 hours and a copper dish gum of 14.0 mg ./l00 cc.

In preparing blends according to the present been removed, and yetprevent the formation of invention other addition a ents may be used,for

2 6 example, metallo-organic antt-knock agents. particularly those ofthe lead alkyl type, c. g. 0.5-6.0 cc. per gallon of fuel, of leadtetraethyl, lead tetramethyl, tin tetraethyl and bismuth trimethyl. n

The following experimental data will iiirther illustrate methods ofcarrying out the invention and advantages obtained by the invention.

Table I C. D. Break- Fuel gum down 1 On ninn 3. l1. 2 5% isoprene in (l)6.0 2. 5 3 0.5 mg. B. A. P.'I100 cc. of 8.0 2. 7 4 mg. B. A. P./l00 cc.0 ll. 0 10. 6 6 20 m B. A. P.'I100 cc. of 15. 0 12+ 6 oprene in (l) 6.00.8 7 0.5 mg. B. A. P.I100 cc. of 9. 0 0.8 8 10 mg. B. A P./l00 cc. of10. 0 5. 1 9 mg. B. A PJHXI cc. of 15.0 4.0

'Beneyl para-amino phenol.

Table II 0. N. O. F. R. Blending 0. N.

Fuel No No 3 cc. No 3 cc.

lead lead/gal. lead lead/gel.

l0 Gasoline 64. 5 81. 1 ll 10 mg. B. A. P. and 5% isoprene (l0) 69. 783. 5 168. 5 129. 1 12 10 mg. B. A. P. and 15% isoprene in (10) 73. 884. 3 126. 5 102. 4

The above Tables I and 11 show that 10 mg. of inhibitor/100 cc. ofgasoline were more than sufficient to produce an isoprene-containingblend of satisfactory copper dish gum and breakdown test as well assatisfactory octane number blending characteristics and good leadsusceptibility.

aaeaase crude base stock) raises the copper dish gum from 4.4 to 6.9 mg.when tested immediately and from 4.1 to 31.5 mg. after 93 days storagein the light. It also shows that the addition of either of theinhibitors (benzyl para-amino phenol or tricresol) resulted in asubstantial stabilization of the blended fuel even when stored in lightfor 93 days (the copper dish gum being 16.7 for the benzyl para-aminophenol inhibitor and 12.1 for the tricresol as compared to 31.5 for theblend without any inhibitor). In tests 17 and 18, the copper dish gumvalues are higher than in the other tests because the benzyl para-aminophenol is so non-volatile that it remains as a residue and thereforeraises the copper dish gum value by an amount practically equal to theweight of the inhibitor used.

From a few additional tests on sludging, it appears that in a fuel towhich butadiene has been added. trioresol is unexpectedly superior tobenzyl para-amino phenol because for some unknown reason the tricresolhas a superior sludge-praventing property in such a blend.

Table 1111) shows that the addition of 5% of butadiene to the plaingasoline base stock lowers the breakdown (a 2# drop from the original100# of oxygen pressure) from about 10 to 2.1 hours but the addition of10 mg. of benzyl para-amino phenol or the same amount of trlcresolraises the breakdown time to more than 15 hours in each case.

It is understood oi. course that other known addition agents may be usedin preparing motor fuels according to the present invention; forinstance, dyes may be added as well as anti-knock agents of other types.Also solvent oils or gum fluxes such as described in the Sloane andWasson Patent 2,066,234 may be added, and these are particularly usefulin a fuel in which substantial Table IIIa C. D. gum, mg./l00 0.0 No 5%dioleiine m Storage 0 days 20 days 56 days 93 days Light... 3.5 5.5 4.1Dark 4. 4 4. 3 5.0 4. 5

Light... 8.8 $1.3 31.5 Dark 6. 9 7. 4 7. 4 7. 7

Light. 18. 6 20. 0 l6. 7 Dark 17. 4 16. 4 19. 7 17. 4

Light... 8.2 8.3 12.1 ark 8. 3 8. 6 9. 8 8. 2

Table 1115 Breakdown, hours for 2! drop No 5% dioleflne 'g f Storage 0days 20 days 56 days 93 days 13 None None... Light l5 10. 14 0.--- D 1012+ 15 Butadiene Light... 2. 0 2. 3 16 do Dark 2.1 2.6 2.6 2.0 17 Light.13. 0 7. 5 l8 Der 15+ 6. 9 14. 0 14+ 19 Light.-. 16+ 14. 1 5. 2 20 Dark15+ 16+ 8. 8 12+ of either benzyl para-amino phenol or tricresol per 100cos. of fuel, when tested immediately as well as over storage during 20,56 and 93 days.

The tests in Table IIIa show that the addition of 5% of butadiene to thegasoline (which was amounts 01. a relatively non-volatile gum inhibitorsuch as benzyl para-amino phenol are used.

In carrying out the present invention, it is desirable to prepare agasoline base stock with less than 2% of hydrocarbons having morealiphatic unsaturation than olefines. In other words, it is desirable torefine either, a virgin or cracked gasoline base stock in such a way asby acid treating, clay treating, treating with aluminum a refinedaviation gasoline obtained from a Pecos chloride, boron fluoride, orother known treating agents, to produce a gasoline base stock containingless than 2% of diolefines, acetylenes, triolefines, and other highlyunsaturated hydrocarbon compounds. If the sulfur content of theresulting base stock is not already low (either by reason of low sulfurcrude having been used or by reason of sulfur removal by any of thetreatments used for removing the highly unsaturated compounds), suitableadditional treatment should be given to reduce the sulfur content downto not more than 0.1% and preferably still lower, to not more than0.01%. The reduction of the sulfur content is highly desirable not onlyfor the obvious reason of reducing the corrosive tendency of the fuelbut also for the even more important purpose of improving the leadsusceptibility because it has been found that the diolefines of thepresent invention have better lead susceptibility octane number basestocks, e. g. those having an octane number as high as 75 Or higher,although in the latter type of fuels the blending octane number of thediolefines is relatively not as high as in the lower octane numberfuels.

It is thus seen that whereas in the usual refining practice usedheretofore in the preparation of gasoline motor fuels the refiningtreatment used to reduce the sulfur content, to reduce corrosion andimprove lead susceptibility, usually also reduces the content ofdiolefines and other highly unsaturated compounds, whereby the valuableoctane-improving and lead susceptibility characteristics of anydiolefines which might have been present would be totally lost, thepresent invention provides a novel and unexpected method of making useof the said valuable characteristics of the diolefines by adding them inpurified form to a suitably purified gasoline base stock. If desired, agasoline base stock such as one obtained by vapor phase cracking of gasoil or other high-boiling hydrocarbons, or any other suitablehydrocarbon fraction rich .in diolefines having from 4 to 10 carbonatoms. can be refined in order to separate the desired diolefinestherefrom in a purified condition. For instance, such a crudedioleflne-containing fraction may be treated with one or more selectivesolvent extraction steps, if desired, with successive treatments withsulfuric acid of successively increasing concentrations, in order toobtain a fraction consisting essentially of diolefines which may inturn, if desired, be still further purified before being used as motorfuel blending agents according to the purview of the present invention.

The invention is not to be limited to the specific embodiments shown orthe specific examples given, nor to any theories advanced as to theoperation of the invention, but in the appended claims it is intended toclaim all inherent novelty in the invention as broadly as the prior artpermits.

We claim:

1. A motor fuel consisting essentially of a cracked gasoline which hasbeen substantially freed of unsaturated aliphatic hydrocarbons havingmore than one double bond per molecule, and which has been reduced to asulfur content of less than 0. said motor fuel also containing about 5to 20% of butadiene, about 0.5 to 20 mg. of tricresol per cos. of fuel,and about 0.5 to 6.0 cos. of lead tetraethyl per gallon of fuel.

2. The method of preparing a motor fuel of improved anti-knock value,high lead susceptibility, and satisfactory stability, which comprises,refining a cracked gasoline base stock to substanin an amount of about5% to 10% by volume, and

a small amount of gum inhibiting phenolic compound.

GEORGE H. FREYERMUTH. ANTHONY E. ROBERTSON.

